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HTML 

              
                <link href='https://fonts.googleapis.com/css?family=Share+Tech&subset=latin,latin-ext' rel='stylesheet' type='text/css'>
<body data-spy="scroll" data-target="#side-nav">
<div class="container">
  <div class="row">
    <div id="side-nav">
      <ul class="nav nav-list affix">
        <li><a href="#start">*Scroll Spy<br><sub>vertical height</sub></a></li>
        <li><a href="#one">N&deg;1</a></li>
        <li><a href="#two">N&deg;2</a></li>
        <li><a href="#three">N&deg;3</a></li>
      </ul>
    </div>
    <div class="col-md-offset-3 col-md-9 content">
      <div id="start" class="h1-wrap">
      <h1 class="shareTech opacity">Scroll Spy Vertical Height Demo</h1>
        <div class="puppyWrap"><div class="puppyCover opacity"></div>
       <img class="topImage" src="http://www.drawing-factory.com/image-files/how-to-draw-a-puppy-labrador11.jpg" />
        </div>
      </div>
      <section id="one">
        <h2 class="shareTech">Section 1</h2>
             <p>
               Scroll spy is very fun but pretty tricky when it's activated by id's with elements of varying heights.
             </p>
      </section>
      <section id="two">
        <h2 class="shareTech">Section 2</h2>
         <p>
           <strong>Note:</strong> If the nav list is of a certain height and is the trigger element well - you could run into problems when consider spy activation.
             </p>
      </section>
      <section id="three">
        <h2 class="shareTech">Section 3</h2>
         <p>
               If you're rendering trigger id elements dynamically it's best to make sure that you're setting the height of the element as well; particularly if the element height is small. 
             </p>
      </section>
      <sub>Disclaimer: this is mainly an issue for desktop viewing so this example will not depercate nicely. You're welcome. ;) The background image is from <a href="http://www.drawing-factory.com/">The Drawing Factory</a>.</sub>
    </div>
  </div>
</div>
</body>
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CSS 

              
                body, body a {
  background:#FAF7FA;
  color: #A76AD9;
}

body .nav-list>.active>a{
  background-color:#DDBFF5;
}
body .nav-list>.active>a:hover {
  background:#A146C2;
}
body .nav a:hover{
  color:#DDBFF5;
  background-color: #F7EDFA;
}
#side-nav {
  position: relative;
  overflow: hidden;
}
#side-nav:before,
#side-nav:after {
  content: ' ';
  display: table;
}
#side-nav:after {
  clear: both;
}

.shareTech {
  font-family: 'Share Tech', sans-serif;
}
.nav-list li a {
  height:80px;
  font-size:2em;
  line-height:80px;
}
.opacity, section {
  opacity:.7;
}
.h1-wrap {
    padding:1em 1em 5em 2em;
    background-color: #F7EDFA;
    margin-bottom:1em;
}
h1:first-of-type {
  color:#A146C2;
  font-size:3em;
  margin-top:1em;
  margin-left:25%;
}
.topImage {
  display:inline-block;
  height:auto;
  width:40%;
  margin-left:30%;
}
.puppyCover {
  background-color: #F5E8FA;
  position:relative;
  width:40%;
  height:332px;
  margin-bottom:-332px;
  margin-left:30%;
}
section {
  background-color: #F2EBF7;
  height:300px;
  margin-bottom:1em;
  padding: 1em 1em .5em 1em;
}
section + section {
  height:220px /* note the section height here! */
}

section + section + section {
  height:400px
}
section h2 {
  font-size:2em;
  line-height:2.5em;
}
section h2:first-letter {
  font-size:3em;
}
section p {
  float:right;
  font-size:1.5em;
  line-height:1.6em;
  width:50%;
}
sub {
  background:#A76AD9;
  color:#fff;
  padding:1em;
  display:block;
  float:right;
  font-size:1em;
  line-height:1.1em;
  margin-bottom:2em;
  margin-right:1em;
  width:50%;
}
sub a {
  background:none;
  color:#fff;
}
sub a:hover {
  color:#fff;
  text-decoration:underline;
}
@media only screen and (max-width: 1200px) { 
  #side-nav, .puppyWrap {display:none;}
  .col-md-offset-3 {
    margin-left: 0;
  }
  .col-md-9 {
    width: 100%;
  }
}
!

JS
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